Commonly, I always use quicktime alternative instead of Apple Quicktime because of its lightweight and I really not need to install a huge and bloat application. Although most of the website that use quicktime work properly, but only facebook doesn’t, the chat in facebook doesn’t have a sound in Firefox.
Quicktime alternative may have some bug but I still hear chat sound in Chrome browser so the Quicktime alternative should work right.
I tried to solve the problem and found that from facebook in reply of Corrie Sherman about “MIME”.
The below is the method that I get facebook sound comeback.
Go to System Control panel > Quicktime > Select to “Browser” tab and click on “MIME Settings…” button below the page.
And then, “Check” for “mp3 audio” and click “OK”. The action is use for associated mp3 file in your browser only not in your system so you still double click mp3 files and it will be opened in your favorite music player as well as you needs.
You may need to restart Firefox before do the following procedure.
Go to Firefox > tools > options > Applications
Find for “mpeg layer 3 (audio/x-mp3)”, “mpeg layer 3 (audio/x-mpeg)” and “mpeg layer 3 (audio/x-mpeg3)” and change it to “Use Quicktime plug-in”.
Finally, try to test it sound in facebook chat, Good luck.